# Package net.sf.saxon.style

This package provides classes used during the compilation of an XSLT stylesheet.

See: Description

- Interface Summary
  Interface | Description
  --- | ---
  CollationDeclaration | Interface implemented by SaxonCollation, which is not available in Saxon-HE
  StylesheetProcedure | This interface is implemented by all XSL elements that can contain local variable declarations.
  XSLTStaticContext | Extends the standard XPath static context with information that is available for XPath expressions invoked from XSLT

- Class Summary
  Class | Description
  --- | ---
  AbsentExtensionElement | This element is a surrogate for an extension element (or indeed an xsl element) for which no implementation is available.
  AttributeValueTemplate | This class represents an attribute value template.
  DataElement | This element represents a top-level element in a user-defined namespace, or a child/descendant of such an element.
  Declaration | The object represents a declaration (that is, a top-level element) in a stylesheet.
  ExpressionContext | An ExpressionContext represents the context for an XPath expression written in the stylesheet.
  ExtensionInstruction | Abstract class representing an extension instruction
  LiteralResultElement | This class represents a literal result element in the style sheet (typically an HTML element to be output).
  PrincipalStylesheetModule | Represents the stylesheet module at the root of the import tree, that is, the module that includes or imports all the others.
  SourceBinding | Helper class for xsl:variable and xsl:param elements.
  StyleElement | Abstract superclass for all element nodes in the stylesheet.
  StyleNodeFactory | Class StyleNodeFactory.
  StylesheetFunctionLibrary | A StylesheetFunctionLibrary contains functions defined by the user in a stylesheet.
  StylesheetModule | A stylesheet module represents a module of a stylesheet.
  UseWhenFilter | This is a filter inserted into the input pipeline for processing stylesheet modules, whose task is to evaluate use-when expressions and discard those parts of the stylesheet module for which the use-when attribute evaluates to false.
  UseWhenStaticContext | This class implements the static context used for evaluating use-when expressions in XSLT 2.0 A new instance of this class is created for each use-when expression encountered; there are therefore no issues with reusability.
  XSLAnalyzeString | An xsl:analyze-string elements in the stylesheet.
  XSLApplyImports | An xsl:apply-imports element in the stylesheet
  XSLApplyTemplates | An xsl:apply-templates element in the stylesheet
  XSLAttribute | xsl:attribute element in stylesheet.
  XSLAttributeSet | An xsl:attribute-set element in the stylesheet.
  XSLCallTemplate | An xsl:call-template element in the stylesheet
  XSLCharacterMap | An xsl:character-map declaration in the stylesheet.
  XSLChoose | An xsl:choose elements in the stylesheet.
  XSLComment | An xsl:comment elements in the stylesheet.
  XSLCopy | Handler for xsl:copy elements in stylesheet.
  XSLCopyOf | An xsl:copy-of element in the stylesheet.
  XSLDecimalFormat | Handler for xsl:decimal-format elements in stylesheet.
  XSLDocument | An xsl:document instruction in the stylesheet.
  XSLElement | An xsl:element element in the stylesheet.
  XSLFallback | xsl:fallback element in stylesheet.
  XSLForEach | Handler for xsl:for-each elements in stylesheet.
  XSLForEachGroup | Handler for xsl:for-each-group elements in stylesheet.
  XSLFunction | Handler for xsl:function elements in stylesheet (XSLT 2.0).
  XSLGeneralIncorporate | Abstract class to represent xsl:include or xsl:import element in the stylesheet.
  XSLGeneralVariable | This class defines common behaviour across xsl:variable, xsl:param, and xsl:with-param
  XSLGlobalParam | An xsl:param element representing a global parameter (stylesheet parameter) in the stylesheet.
  XSLGlobalVariable | Handler for xsl:variable elements appearing as a child of xsl:stylesheet.
  XSLIf | Handler for xsl:if elements in stylesheet.
  XSLImport | xsl:import element in the stylesheet.
  XSLImportSchema | Compile-time representation of an xsl:import-schema declaration in a stylesheet
  XSLInclude | xsl:include element in the stylesheet.
  XSLKey | Handler for xsl:key elements in stylesheet.
  XSLLeafNodeConstructor | Common superclass for XSLT elements whose content template produces a text value: xsl:text, xsl:value-of, xsl:attribute, xsl:comment, xsl:namespace, and xsl:processing-instruction
  XSLLocalParam | An xsl:param element representing a local parameter (template or function parameter) in the stylesheet.
  XSLLocalVariable | Handler for xsl:variable elements acting as local variable declarations in a stylesheet.
  XSLMatchingSubstring | Handler for xsl:matching-substring and xsl:non-matching-substring elements in stylesheet.
  XSLMessage | An xsl:message element in the stylesheet.
  XSLNamespace | An xsl:namespace element in the stylesheet.
  XSLNamespaceAlias | An xsl:namespace-alias element in the stylesheet.
  XSLNextMatch | An xsl:next-match element in the stylesheet
  XSLNumber | An xsl:number element in the stylesheet.
  XSLOtherwise | Handler for xsl:otherwise elements in stylesheet.
  XSLOutput | An xsl:output element in the stylesheet.
  XSLOutputCharacter | An xsl:output-character element in the stylesheet.
  XSLPerformSort | Handler for xsl:perform-sort elements in stylesheet (XSLT 2.0).
  XSLPreserveSpace | An xsl:preserve-space or xsl:strip-space elements in stylesheet.
  XSLProcessingInstruction | An xsl:processing-instruction element in the stylesheet.
  XSLResultDocument | An xsl:result-document element in the stylesheet.
  XSLSequence | An xsl:sequence element in the stylesheet.
  XSLSort | An xsl:sort element in the stylesheet.
  XSLSortOrMergeKey |
  XSLStylesheet | An xsl:stylesheet or xsl:transform element in the stylesheet.
  XSLTemplate | An xsl:template element in the style sheet.
  XSLText | Handler for xsl:text elements in stylesheet.
  XSLValueOf | An xsl:value-of element in the stylesheet.
  XSLWhen | Handler for xsl:when elements in stylesheet.
  XSLWithParam | An xsl:with-param element in the stylesheet.

## Package net.sf.saxon.style Description

This package provides classes used during the compilation of an XSLT stylesheet. The instances of these classes are discarded once compilation is complete, and they play no role in executing the transformation at run-time, except when tracing and debugging are invoked.

The class StyleElement represents an element node on the stylesheet tree. Subclasses of StyleElement represent individual stylesheet elements, and are generally named according to the XSLT element name, for example XSLApplyTemplates, XSLChoose. The class XSLStylesheet is used for the `xsl:stylesheet` element in each stylesheet module, and in particular for the `xsl:stylesheet` element in the principal stylesheet module.

During construction of the stylesheet tree, the class StyleNodeFactory is nominated to the Builder as the factory class responsible for creating element nodes on the tree. It is this class that decides which subclass of StyleElement to use for each element appearing in the stylesheet. For extension elements, the decision is delegated to a user-created ExtensionElementFactory.

Each class provides a number of methods supporting the various phases of processing. The sequence of events sometimes varies slightly, but in general the first phase is done by `prepareAttributes`, which performs local validation of the attributes of each instruction. The second phase is represented by the `validate` method, which does global validation, fixup of references, and type checking. The third phase is done by the `compile` method, which generates `Instruction` and `Expression` objects. Further processing (local and global optimization) is then done on these Instruction objects, and is no longer the responsibility of this package.

Michael H. Kay
Saxonica Limited
9 February 2005

Copyright (c) 2004-2013 Saxonica Limited. All rights reserved.